What is Underneath My Shingles?

What Is Underneath My Shingles?

Like most homeowners, you probably do not put much thought into the roof over your home. Other than cleaning leaves and debris from your eavestroughing or the occasional shoveling of snow from low sloped roof-panels, you probably do not often get a close look at your roof. Did you know that there are many layers that make up a roof? Although all you see when looking at your roof are the shingles, slate or metal on top, the layers of roof beneath are more complex than you might think with multiple layers working together to provide long lasting weather protection and energy efficiency.  Most homeowners typically are not interested in the roofing layers that keep your home dry until after you experience a problem.


There are multiple materials that go into a proper roofing installation, and they must be installed in the right sequence and in the correct manner to keep your home dry while withstanding the harsh weather we experience here in Ottawa.  Although the cost of a new roof relative to the price of your home is small, it is still a large expense for many homeowners, so it is important to remember the importance of each section of your roof regarding how it helps protect the larger investment that is the rest of your home.  In many ways the difference between a roof that lasts only a few years and a roof that last 25 or more years comes down to the small details that cannot be seen, as they exist underneath the shingles or wall metal trim.


Roofing Layers from the Framing to the Shingles

We will start at the bottom of the roof-deck, and work our way up through all the roofing layers until we reach the shingles.

  • Framing – the support beams and  trusses that support the weight of your roof.  When Leaks occur over long periods of time the result is often damage to the framing in the form of warping or rot/mold
  • Insulation - used to reduce the heat loss rising up from your home.  Attic insulation will be found on the attic floor or when the attic is finished, between the rafters over the attic ceiling. When Insulation gets wet due to moisture build-up of leaks it can quickly result in mold issues as the insulation, if left on its own, would take a long time to dry.
  • Ventilation - Critical to your attic, vented intake soffit pulls in new air while roof vents exhaust moisture and stale air. Exhaust vents for bathroom fans also ensures to rid the space of heat and moisture.
  • Roof deck - Most roof decking is made from sheets of plywood, covering over trusses to enclose your attic.
  • Water shield - An adhesive membrane installed up from the bottom of your roof wherever we think water will run or ice will form as well as around any roof protrusions (walls, vents, chimneys)
  • Underlayment - a synthetic woven felt that covers the entire roof deck, designed to allow moisture to pass up through the material but not down.
  • Wall Metal Flashings - underneath the metal trim flashings that can be seen on your roof, there are metal step flashings.  These bent metal flashings overlap each other between each shingle, allowing any water flowing towards your wall to quickly diverted on-top of the shingle beneath.

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